Compound angle cutting edge and method of using same

ABSTRACT

A novel compound angle cutting edge configuration on a die rule, slitter blade, hollow punches, shearing blades, etc. provides cleaner cuts on stock material with less tonnage, improved cutting and cleaner cuts. The die rule cutting edge includes a plurality of side by side notches on only one side of the cutting edge defining a plurality of equally spaced piercing points. A primary cutting edge extends from each piercing point substantially to a next adjacent piercing point and forms a compound angle with an imaginary line through the tips of the piercing points of between about one and fifteen degrees. In use, the cutting edges are axially pressed through stock material to cut blanks of predetermined configuration. The cutting action consists of the piercing points penetrating the material and then the primary cutting edges slicing the stock material from one penetration point, substantially linearly and unidirectionally, to the next adjacent penetration point.

This is a division of application Ser. No. 585,802, filed June 11, 1975now U.S. Pat. No. 3,961,858.

CROSS REFERENCE TO RELATED APPLICATION

This application relates generally to subject matter which was disclosedand claimed in application Ser. No. 793,448, filed Jan. 23, 1969, andnow abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to various cutting tools such asdie rule blades, slitter blades, hollow punches, etc. and moreparticularly to a novel cutting edge configuration.

2. The Prior Art

Several unsolved problems have existed in the art of cutting devicesprior to the present invention. For example, many cutting devices havesomewhat elaborate cutting configurations which are costly to form onthe cutting blade. Many other cutting blade arrangements simply do notgive a clean cut on the stock material as desired.

Still other problems arise in connection with a cutting die press. Forexample, many of the prior art cutting blades require a relatively hightonnage or force to press the cutting blade entirely through the stockmaterial. In die presses where a resilient die pad is used, inordinatewear of the die pad has been experienced with various types of notchedblades because of the cutting blade cutting away the die pad after ithas sliced through the stock material. If a hard metallic back up diepad is used, the cutting blade is dulled by metal-to-metal contact afterthe cutting operation.

Specific examples of prior art cutting blade configurations aredisclosed in U.S. Pat. Nos. 3,277,764 to Henc, 3,422,712 to Lovas, and201,104 to Frary. Each of these prior art devices likewise includeinherent disadvantages not experienced by the present invention.

In short, the prior art does not provide the overall range of advantagesor the structural arrangement or method of cutting edge disclosedherein.

SUMMARY OF THE INVENTION

The present invention relates specifically to an improved compoundcutting edge configuration for die rule blades, slitter blades, hollowpunches, shearing blades, etc. or similar cutting tools. This specificcompound cutting edge configuration enables an improved method ofcutting stock material.

The cutting edge configuration includes a plurality of side-by-sidenotches formed on a chamfered cutting edge portion, thereby forming aplurality of generally equally spaced piercing points or peaks. Aprimary cutting edge is defined which extends into the notch away fromeach peak and toward a next adjacent peak. The present inventioncontemplates that this primary cutting edge will extend substantiallythe entire distance between the two adjacent peaks, providing for asubstantially unidirectional compound slicing or cutting action betweenthe peaks. In a preferred embodiment, the cutting edge forms an anglewith a line connecting the peaks of between about one and fifteendegrees. In the most preferred embodiment, this angle is between about1° and 5°. This relatively small angle forms a shallow notch valleybetween adjacent peaks, which substantially reduces the wear on aresilient backup die pad that may be used in combination with thepresent cutting blade configuration.

It has been found that this novel compound cutting blade configurationof the present invention reduces the pressure required for cutting stockmaterial. This is somewhat surprising since it would be expected thatlarger angles would reduce the rate of cutting and therefore result inless resistance of the stock material to cutting.

In a preferred embodiment of the invention, each notch is formedindividually by placing the cutting tool against a grinding edge. Thisforms major and minor compound angle pyramidal-shaped notch faces. Themajor notch face includes the primary cutting edge and the minor notchface forms a secondary cutting edge which interconnects the primary edgewith the next adjacent piercing point.

The method of using the novel compound cutting edge of the presentinvention includes first placing stock material in alignment with thecutting tool, which is then moved under pressure toward the stockmaterial. First contact between the cutting tool and the stock materialis by the cutting edge piercing points which penetrate the material andinitiate the cutting action. This initial penetration or piercingcontributes to the overall reduction in pressure required for cutting bythe present invention, as will be appreciated by those in the art. Thecontinued movement of the compound cutting tool through the stockmaterial results in the primary cutting edges slicing the stock materialsubstantially unidirectionally from one piercing point to the nextadjacent piercing point. A minimal amount of cutting is accomplished bythe secondary cutting edge which interconnects the primary cutting edgewith the next adjacent piercing point. Axial movement of the cuttingtool is continued until the stock material is completely cut into thedesired configuration.

One preferred application of the present cutting edge configuration ison a cutting die rule that is used in combination with a resilient backup die pad underneath the stock material. In this arrangement, thepiercing points and cutting edges must extend completely through thestock material and into the die pad for a depth which is at least equalto the depth of the notch valley between the piercing points. Since thepresent invention enables a relatively shallow notch valley depth, thepenetration into the die pad is reduced, resulting in increased die padlife.

This novel cutting configuration can be used in a wide variety ofapplications including die rule blades, shearing blades, slitter blades,hollow punches, rotary hole saws, etc. Additionally, the presentinvention may be used quite satisfactorily to cut a wide range ofmaterials, including for example, fiberglass, fabrics, foam rubber,paper, surgical pads, sheet material including vinyl fibers, aluminum,plastics, and various and numerous types of textile goods. This extremewide-range utility of the present invention can therefore beappreciated.

Many advantages have also been found to follow from the presentinvention. First, less tonnage or pressure is required to press thecutting tool through the stock material. This enables smaller powermeans with an associated reduction in cost. Additionally, the lowertonnage requirement results in longer life of the cutting tool,increased production, less maintenance and machine down time isobtained, since reduced pressure is developed at the cutting edge.

Another advantage is the cleaner, straighter cuts that are accomplishedby the present invention. Additionally, the notched compound cuttingedge configuration is relatively simple to form and can be done, forexample, by grinding. As previously discussed, another advantageafforded by the present invention is longevity of the back up cuttingdie pad.

Other advantages are particular to the individual stock material beingcut. For example, in cutting fiber glass it has been found thatapproximately eighty percent less dust is generated during cutting.Fibers in vinyl and other fiber materials are not fused together,because of less heat generated during the cutting action, resulting fromcleaner cutting while the reduced pressure is exerted on the cuttingtool.

Cutting cylindrical holes in foam with prior art cutting instrumentsgenerally results in a concave-shaped cut along the thickness of thestock material. This is due to the cutting instrument compressing thefoam material before the cutting action actually begins. The presentinvention eliminates the concave or convex holes or end cuts andprovides a straighter cut for foam materials because the piercing pointsinitiate the cutting action and reduces the foam compression.

Other advantages and meritorious features of this invention will morefully appear from the following specifications, claims and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, cross-sectional view of a die press whichincludes a cutting tool having the cutting edge configuration of thepresent invention;

FIG. 2 is a perspective view of the cutting tool of FIG. 1;

FIG. 3 is a schematic, partially cross-sectional view of another diepress and cutting tool in combination with a punch tool;

FIG. 4 is a perspective view of the cutting tool in FIG. 3;

FIGS. 5-10 are perspective views of various cutting tools which mayinclude the cutting configuration of the present invention;

FIG. 11 is an enlarged, fragmented plan view of one embodiment of thecutting edge configuration;

FIG. 12 is an enlarged, fragmented side elevational view of the cuttingedge configuration of FIG. 11;

FIG. 13 is a cross-sectional view taken along plane 13--13 of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 illustrates a cutting press 10which is primarily suited for use in cutting thick or tough materials,such as soft metallic materials. The die press 10 includes a fixed diebase 12 surmounted by and connected to mounting plate 14 in aconventional manner. A male punch 16 and a resilient stripper pad 18 issuitably mounted on top of mounting plate 14 for receiving stockmaterial 20. The stock material is cut with a flat die rule 22 which isshown in perspective in FIG. 2. The cutting edge of die rule 22 includesa plurality of side-by-side notched configurations 23 which form a novelcutting edge that will be more fully explained below.

Die rule 22 is mounted in a die rule mounting block 24, which isillustrated as being a wood block. Mounting block 24 is suitably mountedto a back up plate 26 which is connected to a punch holder 28. Acompressible stripper pad 30 is also attached to mounting block 24 inconventional manner and comprises, for example, hard rubber as issomewhat conventional in the art. The die rule 22, stripper pad 30,mounting block 24, back up plate 26, and punch holder 28 comprise avertically reciprocal cutting die.

Operation of the embodiment of FIG. 1 includes raising the cutting dieso that a piece of stock material 20 may be properly positioned on malepunch 16 and stripper pad 18. The cutter die is then driven underpressure downwardly so that the die blade 22 severs the stock materialto form a blank of predesired configuration, thereby leaving scrapmaterial 33. As illustrated, die rule blade 22 cuts through the stockmaterial and barely extends into a slot 32 defined between punch 16 andstripper pad 18. Downward movement of the die press is limitedsubstantially to the position shown in FIG. 1, so that the cutting edgeon rule 23 does not strike mounting plate 14. As the die rule blade 22projects into slot 32, the stripper pad 30 is compressed. Then as thedie press is raised, stripper pad 30 expands and leaves the cut stockmaterial on punch 16.

FIG. 3 illustrates a die press primarily suited for cutting soft stockmaterial. This embodiment includes a fixed base 42 and a verticallyreciprocable punch holder 44 to which back up plate 46, mounting block48, and die rule blade 50 are mounted. In this particular embodiment,the die rule blade is cylindrical as shown in FIG. 4 and includes aplurality of side-by-side notches 52 in accordance with the presentinvention. Also in this embodiment, a punch 54 is suitably mounted inmounting block 48, and may include the cutting edge configuration ofthis invention.

In operation of the embodiment in FIG. 3, the punch holder 44 is raisedfrom the position illustrated and a piece of stock material 56 isproperly positioned on a resilient die pad 58. Die pad 58 is suitablymounted on the fixed base 42 and is comprised of a rubber orpolyurethane material. Scrap material is formed during the cuttingoperation by punch 54, the scrap being removed through a knock-out hole60 in punch 54, as is conventional.

After the stock material is properly positioned on the die pad, punch 54is moved under pressure by suitable power means, such as a hydrauliccylinder and piston, to drive the die rule cutting blade through thestock material 56. At about the same time, punch 54 forms a scrap slug.

As shown in FIG. 3, the die rule cutting edge barely cuts into the diepad. This is necessary so that the notched configuration of the cuttingedge in the present invention will completely cut through the stockmaterial. However, in later portions of this disclosure, it will beexplained that the present invention limits the extent to which the dierule cuts into the die pad, thereby yielding one of the advantages ofthe present invention; i.e., greater die pad longevity, with very littleresurfacing required.

From the embodiments shown in FIGS. 1 and 3, it can be readily seen thatthe cutting edge configuration of this invention can be used in avariety of ways. FIGS. 5-10 further illustrate that the cutting edgeconfiguration is not limited to a die rule, per se, but is virtuallyunlimited in its application. For example, FIG. 5 illustrates a circularhole saw 70 having a shaft 71 and being conventional in every respectexcept the novel cutting edge configuration 72 of the present invention.

FIG. 6 illustrates a flat die rule blade similar to that of FIG. 2 andincluding a shank 74. A chamfer 75 at the cutting edge of the die ruleis formed by two converging, generally V-shaped surfaces. The novelcutting edge configuration of this invention is formed on the chamfer 75and includes the plurality of notches and side-by-side peaks 76.

FIGS. 7 and 8 illustrate cylindrical die rules, or punches, 78 and 82having respective chamfer regions 79 and 83. In these embodiments, theinternal bore of the die rule is generally cylindrical, but there stillexists two converging surfaces to define the cutting edge. Notches 80and 84 are formed on the terminus of the cylindrical die rules to definethe cutting edge configuration of this invention. Each punch includes aknockout hole 77 and 85, respectively, for scrap material ejection.

FIG. 9 illustrates a slitter wheel 86 including a circular hole 87 andbeing conventional in every respect except for the cutting edgeconfiguration 88 of the present invention. As is known to those who areskilled in the cutting art, a slitter wheel traverses stock materialunder pressure to effect the cutting operation.

FIG. 10 illustrates another version of a cylindrical die rule 90 whichis substantially similar to die rule 50 illustrated in FIG. 4. Ofcourse, the cutting edge configuration 92 is that of the presentinvention.

For a complete description of the cutting edge configuration, referenceis now made to FIGS. 11-13, which shows in enlarged fashion, the presentinvention. From FIG. 11, it can be seen that the illustrated tool is acylindrical die rule 100, similar to that in FIG. 10. The die rule 100includes a shank 102 and a chamfer formed by converging surfaces 104 and106. FIG. 13 shows the converging sides forming an angle C, which inpreferred embodiment, should be chosen to fall in the range of betweenone and thirty degrees. As discussed previously in regard to FIGS. 7 and8, surface 104 could be cylindrical, but there would still exist twoconverging surfaces to define the die rule cutting region.

In accordance with the present invention, the cutting edge configurationincludes side-by-side notches or indentations which are formed on onlyone of the chamfer converging surfaces, for example, by grinding. Thesenotches define a plurality of generally equally spaced peaks 108 whichserve to pierce the stock material to initiate the cutting action. Thenotches are also configured to form a plurality of primary cutting orslicing edges 110, each extending away from one peak into an associatednotch and toward a next adjacent peak. It can be seen from FIG. 12, thatcutting blade edge 110 extends approximately 75 to 80 percent or more ofthe distance between two adjacent peaks. For purposes of defining thepresent invention, it is considered that this constitutes the primarycutting edge extending substantially across the entire distance betweentwo adjacent peaks.

Further, it can be seen from FIG. 12 that the primary cutting edge 110forms an angle b with a line through piercing points 108. According tothe invention, this angle should be no more than about 15°. Morepreferably, the angle should be within the range of between about 1° and5°.

FIG. 11 also shows that cutting edge 110 forms an angle a in plan viewwith a line through peaks 108. This angle is directly related, ingeneral, to the slope angle of surface 104 relative to the vertical.This relationship can be seen in FIG. 13, wherein the notch isillustrated in phantom. In most instances, this angle a will be betweenabout 1° and 15°, but this is not critical. In die rule embodimentshaving a cylindrical inner bore, such as in FIGS. 7 and 8, angle a wouldappear to approach zero for strict geometrical reasons.

The notched configuration of the present invention also defines a pairof pyramidal notch surfaces 112 and 114 and an incidentally-occurringsecondary cutting edge 116. The secondary cutting edge, of course, cutsonly small portions of the stock material so that the cutting action issubstantially unidirectionally along primary cutting edge 110 from onepiercing point to the next. In some embodiments, edge 116 may evenbecome purely vertical so that the entire cutting action is along aprimary cutting edge 110. For definitional purposes, surfaces 110 and116 are considered to constitute a checkmarked shaped edgeinterconnecting adjacent piercing points.

Pyrimidal-shaped surface 112, the major pyramidal surface, is bounded onone side by primary cutting edge 110 and has a common side withsecondary pyramidal surface 114. For definitional purposes, thesesurfaces are considered to define a generally boomerang-shaped notchconfiguration. However, it is not necessary that the notches be definedby these pyramidal surfaces. The important consideration would appear tobe the combination of the piercing points, the major cutting edgesestablishing progressive angular cutting from one piercing point to thenext, and the notches being formed on only one side of the chamfer.

FIG. 12 also illustrates that the small angle b defines a relativelyshallow valley depth d. This depth will, of course, be a direct resultof the angle b and the distance between adjacent piercing points. Formost applications of the present invention, this depth will not be morethan about three sixteenths (3/16) of an inch. In the more preferredembodiments, the depth of the valley will be no more than about 3/32,and may even be as shallow as 1/32 and 1/64 of an inch, depending uponthe material to be cut. In the most preferred embodiment, the valleydepth will result from angle 6 being between about 1° and 5°. It will berecalled from the discussion relating to the embodiment of FIG. 3 thatthis shallow valley depth has great significance when a resilient backup die pad supports the stock material. Specifically, for a notched dierule blade to completely cut through stock material the cutting edgeportion must project completely through the stock material and thereforeinto the resilient die pad material. This penetration depth is minimizedin the present invention because of the shallow notch valley depth.Accordingly, the resilient die pad does not experience the wearassociated with prior art notched cutting edges.

The manner of using a cutting tool having the present cutting edgeconfiguration is substantially identical to that of prior cutting tools.However, the cutting action created by the present invention is not thesame as in the prior art. Specifically, when the cutting tool is pressedinto the stock material peaks 108 pierce the material to initiate thecutting action. Continued movement of the cutting tool through the stockmaterial results in a progressive cutting or slicing by the primarycutting edge substantially unidirectionally from one piercing point tothe next. Further, the piercing points and primary cutting edges areformed by a notch which is only on one side of the cutting tool so thatstock material exerts a resistive pressure substantially on only oneside of the cutting tool which creates a unidirectional cutting pressureon the material being cut. These overall structural limitations andcutting method steps result in the reduced tonnage requirementspreviously explained.

It will be understood from the foregoing description that the rate oramount of cutting action in the direction between the pierced points onthe stock material will be dependent upon the angle of the cuttingedges. Specifically, the cotangent for a one degree cutting edge is57.29, the cotangent for a five degree cutting edge is 11.43 and thecotangent for a fifteen degree cutting edge is 3.73. Therefore, with aone degree cutting edge, the stock material will be cut at a rate ofabout 57.29 times the rate of relative movement between the cutting tooland stock material; with a five degree cutting edge, the stock materialbetween the pierced positions will be cut at a rate of about 11.43 timesthe rate of relative movement between the cutting tool and stockmaterial; and with a fifteen degree cutting edge, the stock materialbetween the pierced positions will be cut by an amount in comparisonwith the extent of relative movement between the cutting tool and stockmaterial of about 3.73:1.

It is to be understood that the description and explanation herein ismerely exemplary of the overall invention and is not intended to belimiting in any respect. For example, the cutting edge configuration maybe formed by other methods than grinding and may be used in allequivalent cutting tools.

Having completely and thoroughly described our invention, we now claim:
 1. In a method of cutting blanks from stock material, the steps of positioning the stock material in alignment with a die rule, relatively moving the die rule and stock material toward one another, initially contacting the stock material by a plurality of generally equally spaced peaks on a cutting portion of the die rule, thereby piercing the stock material at a plurality of generally equally spaced positions, continuing to relatively move the material and the die rule and cutting the stock material between the plurality of pierced positions with a plurality of cutting edges, each of said primary cutting edges (a) extending from one piercing peak substantially the entire distance to the next piercing peak and (b) extending away from the stock material by an angle of from about one to fifteen degrees with a line connecting the piercing peaks said cutting edges thereby progressively cutting the stock material substantially unidirectionally from one pierced position progressively toward a next adjacent pierced position by an amount in comparison with the extent of relative movement between the cutting tool and stock material within the ratios of between about 57.29:1 and 3.73:1.
 2. In a method of cutting stock material, the steps of:positioning the stock material on a resilient die pad in alignment with a cutting die rule, said die rule having a chamfered portion defined by two converging surfaces which intersect to form a cutting portion, said cutting portion having formed thereon a plurality of notches which define a plurality of generally equally spaced piercing points and a plurality of substantially linear primary cutting edges extending from each piercing point substantially the entire distance to an adjacent piercing point, said primary cutting edges extending away from said piercing points by an angle of no more than fifteen degrees, thereby forming a valley on the cutting portion between each piercing point, said valley having a depth of no more than three sixteenths of an inch; relatively moving the stock material and the die rule toward one another, and in a substantially simultaneous, sequential operation (a) initially penetrating the stock material at a plurality of positions with the die rule piercing points, (b) cutting the stock material with the primary cutting edges in a direction away from each initially penetrated position toward a next adjacent penetrated position, whereby the stock material between each penetrated position is cut substantially the entire distance therebetween in a progressive cutting action in substantially only one direction at a rate of greater than 3.73 times the rate of relative movement between the stock material and the die rule, due to the angle of the primary cutting edges, and (c) pressing the piercing points through the stock material and into the resilient die pad by a distance of not more than about three sixteenths of an inch due to the shallow valley depth on the cutting portion, at which depth the stock material will be cut through its entire depth by the cutting edges; and retracting the stock material from the die rule and die pad.
 3. In a method of cutting blanks from stock material, the steps of:positioning the stock material in alignment with a cutting tool having a pair of converging side faces; relatively moving the cutting tool and stock material toward one another (a) to initially pierce the stock material at a plurality of generally equally spaced positions by a plurality of generally equally spaced peaks on a cutting portion of the cutting tool, and thereafter (b) to progressively cut the stock material substantially unidirectionally from each of the pierced positions toward a next adjacent pierced position with a plurality of primary cutting edges on the cutting tool, each of said primary cutting edges extending from one piercing peak substantially the entire distance to the next piercing peak and extending away from the stock material by an angle of from about 1° to 5° with a line connecting the piercing peaks and (c) to cut the stock material between the pierced positions at rate of between about 11.43 and 57.29 times the rate of relative movement between the cutting tool and stock material. 